Drum coater with forced recirculation of the material

ABSTRACT

The invention relates to a device for depositing a surface coating on cores. The inventive device comprises a rotationally mounted drum for accommodating the cores, at least one spraying nozzle for depositing the surface material on the cores, a heating device for the inner space of the drum, an inlet and an outlet, and carriers which are provided for the cores and which are arranged inside said drum. The invention provides that the drum is designed as a longish cylinder and that second carriers are provided for the cores ( 11, 12 ). The second carriers transport the cores opposite the first carriers and are arranged such that they can be radially displaced in relation to the first carriers. The invention also provides that the drum is held in the device so that it can be quickly removed.

The invention concerns an apparatus for applying a surface coating tocores.

A device of this type is known from EP-A-0 744 212.

In practical operation, in the case of the known device, in particularin the case of oblong shaped items, not to be excluded is that theseitems that frequently display rectilinear lateral surface have contactwith one another over a longer line, or even over a greater area. Withthe circulating movement of the product inside the drum, the fluidlyapplied coating in the case of this type of intensive contact of twoadjacent items can lead to their adhering to each other, in particularsince, in practice, frequently found within the circulated product is a“dead zone” in the center of the product, inside of which the items arehardly moved. In the case of the known device, to minimize this regionthe drum is embodied with an axial length that is greater than to thediameter of the drum, so that obtained overall is an oblong cylinder. Bymeans of this oblong embodiment, the product is distributed over agreater length of the cylinder, so that the circulated bed of theproduct displays at its interior a small “dead zone.”

Known from FR-A-1 459 246 is a coating apparatus whose drum displaysfirst carriers that do not impart to the product any forward feed in theaxial direction of the drum, hence produce no axial transport, rathertransporting the product exclusively transversely to the axis of thedrum in a rotary movement about the drum axis, hence in the form of acirculation or circumferential transport. Second carriers are providedspaced inwardly out from the drum wall and produce an axial transport ofthe product inside the drum in the longitudinal direction of the drum.Since the drum is disposed horizontally, axial transport of the coatingproduct is effected exclusively through the second carriers.

The object of the invention is to improve an apparatus of this genresuch that it assures as thorough as possible circulation of the product.

The object of the invention is met through an apparatus with a rotatablymounted drum for accepting the cores, with at least one spray nozzle fordeposit of the surface material onto the core, as well as with a heatingdevice for the inside space of the drum, as well as with an inlet and anoutlet opening, as well as with canters arranged in the drum cores,characterized by the fact that the drum (7) is embodied as an oblongcylinder, and that second carriers (12) are provided for the cores,which transport the cores in a direction opposed to the direction of thefirst carriers (11), and that are radially offset relative to the firstcarriers (11), and that the drum (7) is journaled in the apparatus (1)in quickly removable fashion.

In other words, additionally to the first carriers lying inside at thepheriphery of the drum, which transport the product in one directionalong the longitudinal axis of the drum, the invention proposes toprovide opposed-acting second carriers that are not arranged alternatelybut rather are radially offset, for example further toward the interiorof the drum. Since these carriers are supported on brackets against thedrum wall, the product can be transported under these carriers along thedrum wall by the first carriers. However, the regions of the producthaving a greater layer thickness are picked up by the second carriers,and since these second carriers act in opposed fashion with the firstcarriers a more intensive, thorough mixing of the bed is effected, sothat a “dead zone” can be minimized, and, depending upon the geometry ofthe carriers and the drum, can be practically regularly excluded, namelyif the coating results yield no items stuck together.

Designated as cylinders within the idea of this invention are not onlydrum shapes with a circular cross section, but also with a polygonal,for example an octagonal cross section.

The drum can advantageously be planned to be removably mounted in theapparatus. In this manner, even in operation of the apparatus with onlyone drum, a high degree of system availability can be assured, namely inthat a soiled drum, even in the case of considerable expense andcorrespondingly great time requirement, can be replaced within a shorttime with a cleaned drum. Hence, the cleaning times, with comparativelylow financial expense through procurement of a single replacement drum,do not correspond to the down times of the entire apparatus, so that,all together, the apparatus can be operated with considerably improvedeconomy.

The drum can advantageously be planned to be tiltably supported in itslongitudinal axis so that it can be operated in a slanted arrangement.In this manner, automatically assured is that the items inside the drumwill be optimally, thoroughly mixed and again always picked up by thecarriers and moved through each other.

Advantageously, the first, upwardly-transporting carriers in the case ofthis type of diagonal operation of the drum can be arranged, in a mannerknown per se, along the drum wall, while the second,opposed-transporting carriers are supported against the drum wall, andare correspondingly radially further inside. In this way, the drum, in amanner known per se, can be embodied in more price-favorable fashion,and the second carriers can be added later.

With corresponding space planning, the apparatus can advantageouslydisplay several drums that operate connected one after another, so thatthe individual coating steps can run off after one another in a drumthat is special for each step. In this manner, optimal treatmentconditions can be set in the individual drums; the degree of soiling ofeach one of the drums can be correspondingly reduced.

An example of embodiment of the invention will be described in moredetail in the following with the aid of the drawings. Shown are:

FIG. 1 a perspective view of an apparatus with closed covering hood,

FIG. 2 the apparatus of FIG. 1 with open covering hood, and

FIG. 3 a view axially into the interior of the drum.

Denoted generally with 1 in FIG. 1 is an apparatus that is designated asa “Drum Coater.” The apparatus 1 displays a support foot 2 on which itis disposed in tiltably moveable fashion about a tilt axis 3. Thetilting movement is made possible through a hydraulic, telescopingsupport 4. An inlet opening 5 is provided on the front side of theapparatus 1; it also serves as an outlet opening.

Seen from FIG. 2 is that the apparatus displays a swingable coveringhood 6 under which is provided a drum 7. With its one end, the drum 7rests on rollers 8, with limit rollers 9 also being provided on thefront side. On its other end, the drum 7 displays a gear ring 10 throughwhich the drum can be driven in rotating fashion. Along its cylindricalcircumference, the drum is made of previous material, for example aperforated sheet metal. First carriers 11 are provided as a single ormultiple spiral, and attached directly to the drum wall.

Seen from FIG. 2 is that provided additionally to the first carriers 11are second carriers 12, which are likewise embodied as spirals whoselead, however, runs opposite to that of the carriers 11. The secondcarriers 12 are attached on brackets 14, at a distance from the drumwall, and therefore lie radially inside the first carriers 11.

What is claimed is:
 1. An apparatus for applying a surface coating tocores comprising: a rotatably mounted drum for accepting the cores; atleast one spray nozzle for deposit of the surface material onto thecore; a heating device for the inside space of the drum; an inlet and anoutlet opening; and at least one first and at least one second carrierarranged in the drum, wherein said drum is an oblong cylinder, whereinsaid at least one second carrier transports the cores in a directionopposed to the direction of said at least one first carrier, and whereinsaid at least one second carrier is radially offset, and further towardthe interior of the drum relative to said at least one first carrier,and wherein the drum is journaled in the apparatus in a quicklyremovable fashion.
 2. The apparatus of claim 1, wherein the drum ismounted in tiltable fashion, and is capable of being driven in anarrangement of its longitudinal axis that is slanted relative to thehorizontal.
 3. The apparatus of claim 2, wherein the at least one firstcarrier is arranged in an upwardly transporting manner, and disposedradially outside of the at least one second carrier.
 4. The apparatus ofclaim 1, further comprising at least two drums.
 5. The apparatus ofclaim 4, wherein said at least two or more drums are provided axiallybehind each other, with closable passages being provided between eachtwo adjacent drums.